Die of the extruding and wire drawing type and process of making the same



DIE F THE EXTRUDING Patented Aug.' 4, 1931 ,PATENT OFFICE UNITED STATESJOHNLT. PRATT, or 'NEW Yoan,-

EXECUTORS OF SAIDJO N. Y.; nanou I. PnATrAND RUTH BAKER PRATT :1N Ir.'`rR-A'r'r, DnenAsEn AND lWIRE DRAWING-TYPE AND rnocnss or name SAME jApplication filed vNovember '28, '1925. Serial No. 72,020.

" This invention relates to dies, pa-rticularly of the typehaving smallrecesses or apertures, such as wire ing dies, and toprocesses ofmanufacturing the same, and aims toV provide improvements therein.

The wear on extruding of increasing `the durability of these dies byapplying a plate ofV chromium thereto has .been recognized, but greatdifficulty ha-s been experienced in applying an even, adherent andsmooth plate of chromium to the working faces thereof. Y

The present invention provides a way around this difliculty: it providesa-novel ldiehavim'; a chromium working face or surface which is smooth,even and adherent, and processesfor producing such novel die.

Several embodiments of the die are illus-A trated in the accompanyingdrawings'. Said drawings also contain figures illustrative of theprocesses.

. Referring to saiddrawings:

Figure 1 is a sectional view of one embodiment of said die. Fig. 2 is asectional view of another embodiment of said die.

Fig..3-is` a sectional view ofstill another embodiment of said die. 1

Figs.' 4, 5 and 6 are views illustrative of the processes.

Referring to said drawings, designates the die, comprising a `a backing14. The shell 12 is composed in numeral 10 Y whole or inpart-ofchromiunr or other very vplied in any suitable shell 12. Theformed matrix or counter-part is`then placed in a chromium to asubstantial thickness-U64 drawing dies and extrud or wire drawingv diesis very considerable and the desirability shell 12 and bath and platedwithI to'1/16'inch, for4 example. This plating may be effected by anysuitable process. The fine quality of plate which is produced withchromlc Vacid baths according to the tempJeraStures and currentdensities set forth in Fink, is most suitably used. The inside or.working face of the chromium shell will,

when ofthe quality of plate produced by said Fink process, have asmoothness and polish equal to that of 'the polished matrix.

Patent No. 1,802,463, April 28, 1931,-

l/Vhen a sufficient quantity of chromium has i sir'ed thickness, thedeposition is discontinued. and the shell 12 separated from the matrixin suitable manner, as by dissolving in' nitric acid, or by melting outthe matrix. Where melting is resorted to, a low-melting brass, or one ofthe so-'called low-.melting alloys, such as white-metal, is used for thematrix.

Oxidation may be prevented by melting in a neutral or inert atmosphere,

lead.

The backing 14, may consist of a piece of metalto which the shell A12 isfitted, in suitable manner', as by tool-shaping the backmg with `arecess 20 or 22 corresponding to or `in a bath of lbeen deposited toform a shell of thedethe outside dimensions of theshell, (Figs. V1 y and2) or by setting or solidifying molten metal around the shell, asindicated at 26, Fig. v3. The solidified metal 26 may con stitute thebacking alone, or the backing may be composite,

which may serve as a receptacle for the metal 26 while molten, and unitewith the shell 12 and metal 26 on solidification taking place.

Suitable means 30 for holding the shell 12 in the backing maybeprovided. vThese meansmay be used for the purpose ofv preventing'Aseparation of the shell and backing,

and comprise a metal cup 28,.

as when a let-up or relaxation occurs in the drawing of the wirevpassing through the aperture 18 in the shell. These means areconveniently in the form of `cap-screws 82 tapped into the backing' andthe heads of which overlap the edges of the shell-12, as showninvFigs. 1and 2. The film of metal of the backing 26 adhering to the shell 1'2acts as the means for holding thel shell and backing together in thatembodiment where also serves as a metal which may be readil the .backingis metal which is 'solidified around the shell. Y

The sides 35 of 4the backing are preferably tapered so as to fit withinthe seat in the dieblock of the drawing mill.l

When the fitting of the shell 12 in the backing is effected bytool-shaping,.the final f1tting, in order to obtain a very solid andeven bearin ofthe shell in the recessis preferably e ected by grindingvthe shell in the recess, with the aid of an abrasive, as well unl"derstood, the grinding bei'ng similar to the grinding of valves tovalve seats.

After the deposition of chromium to form the shell 12 has beencompleted, a layer 40 of another metal, as for example, electrolyticiron, may be deposited on the back side of the chromium shell, as shownin F ig. 6. This layer 40 may serve a number of functions. It may serveto support` and strengthen the chromium shell 12. It may serve as asofter metal -to facilitate the shaping of the outer surface of theshell 12 to the recess 22 in the backing. It may also serve as a meansfacilitating the bond between the shell 12 and the solidified metal 26around it. The layer 40 Worked to give the outer surface ofthe shell adifferent or more regular shape (conical for example) than the workingfaceof the shell, so that the recess 20 may be correspondingly shapedand the fitting of the shell 12- and backing 14 facilitated. The innerface of a Wire drawing die is usually -funnel shaped as shown, and theprincipal stress is on` the shoulder 55. By shaping the metal layer 40on the back side of the shell 12 as a cone,

the maximum thickness of metal and conseuently the maximum support isbehind the ghoulder 55, where most needed. The full taper to the apex ofthe shell also serves to support the part of the die ahead of theshoulder 55, as well as the part behind it.

Where there is a ground fit between the shell and backing, the softermetal layer 40 on the back side of the shell 12 facilitates thegrinding.

The soudity and fullness'of fit of the Shen 12 in the recess 22 may befurthered by interposing a foil of soft metal, as indicated by thethickened lines 60, Fig. 2.

The invention may receive other embodiments than those herein specicallyillustrated and described, and the process may be carried out byothermodes of procedure than those specifically described.

What is claimed is:

1. A die having a relatively small aperture or recess, and difficult toform by deposition of a hard metal on a foundation-metal, comprising aseparately formedchromium shell,

- and a backing for said shell.

2. A`process of forming a die of the type having a relatively smallaperture or recess and diicult to form by deposition of a hard www metalon a foundation'metal, comprising depositing chromium upon a matrix orcounterpart vhaving the sha of the working face of lthe die, and, builing up a shell thereon,

l and electrodepositing iron on the back of said shell to form abacking.-

3. die according to claim 1 in which thel backmg for the shell isconstituted of electro- `deposited iron.

deposition of chromium until a plate of the4 desired thickness has beenmade, and removing said plated form from the electroplating tank,treating the same with an acid reagent capable of dissolving saidmetallic form to produce a shell of electrodeposited chroy mmm.

6. The process of producing a hollow die of the extruding andWire-drawing type which comprises making a cathode of a substancecapable of subsequent removal, electrodepositing chromium on theexterior of said cathode, continuing the electrodeposition of chromiumuntil a shell is formed, then removing said cathode and shell ofelectrodeposited chromium from the electroplating tank, converting thesubstance constituting the cathode into a fluid form to cause theremoval thereof from the shell of electrodeposited chromium andsurrounding the outside of the shell of electrodeposited chromium with alayer of softer metal to reinforce said shell.

7. The process as set forth in claim 6 in which the softer metal has arelatively low melting point.

8. A process of forming dies of the type having a relatively smallaperture or recess and diiiicult to form by deposition of a hard metalon a foundation metal, comprising depositing the hard metal upon amatrix or counterpart having the shape of the working face of the die,said die having tapered faces and having a relatively small aperture orrecess at the end of said tapered faces, depositing a chromium shellthereon, and surrounding the exterior of said shell with a relativelysoft metal capable of being readily worked.

In witness whereof, I have hereunto signed my name.

JOHN T. PRATT.

